the audio quality is good, the video playback is good and actually depends on the quality of the original file, you can watch videos clearly, if you experience videos jerking or the picture is bad, its not due to the player but due to bad converting.

Check your player when you get it, try and copy 2gb worth of stuff, but then try and access all 2gb worth of stuff, you don't need to do this on the player, just access the files you copied on your player via windows explorer and try to open/play them, if they all work, then you have a real 2gb player, if you get any error messages, you got a hacked player.

If you get a hacked player, don't alter it, contact the ebay seller and send it back and get your money back.